/usr/share/octave/packages/3.2/tsa-4.1.0/histo3.m is in octave-tsa 4.1.0+svn20110501-1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 | function [R,tix]=histo3(Y)
% HISTO3 calculates histogram and performs data compression
%
% R = HISTO3(Y)
% R is a struct with th fields
% R.X are the bin-values
% R.H is the frequency of occurence of value X
% R.N are the number of valid (not NaN) samples
%
% Data compression can be performed in this way
% [R,tix] = histo3(Y)
% is the compression step
%
% R.tix provides a compressed data representation.
% R.compressionratio estimates the compression ratio
%
% R.X(tix) and R.X(R.tix)
% reconstruct the orginal signal (decompression)
%
% The effort (in memory and speed) for compression is O(n*log(n)).
% The effort (in memory and speed) for decompression is O(n) only.
%
% see also: HISTO, HISTO2, HISTO3, HISTO4
%
% REFERENCE(S):
% C.E. Shannon and W. Weaver "The mathematical theory of communication" University of Illinois Press, Urbana 1949 (reprint 1963).
% $Id: histo3.m 5090 2008-06-05 08:12:04Z schloegl $
% Copyright (C) 1996-2002,2008 by Alois Schloegl <a.schloegl@ieee.org>
% This is part of the TSA-toolbox. See also
% http://hci.tugraz.at/schloegl/matlab/tsa/
% http://octave.sourceforge.net/
% http://biosig.sourceforge.net/
%
% This program is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
%
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with this program. If not, see <http://www.gnu.org/licenses/>.
[yr,yc]=size(Y);
if yr==1,
% Makes sure there is a second row
% Sort does not support the DIM-argument, therefore,
% this function would not work correctly with this software
% Once this is fixed, this part can be removed.
Y = [Y; NaN+ones(size(Y))];
end;
% identify all possible X's and overall Histogram
[sY ,idx] = sort(Y(:));
[tmp,idx] = sort(idx); % generate inverse index
ix = diff(sY,1)>0;
tmp = [find(ix); sum(~isnan(sY))];
H = diff([0; tmp]);
R.datatype = 'HISTOGRAM';
R.X = sY(tmp);
R.N = sum(~isnan(Y),1);
% generate inverse index
if nargout>1,
tix = cumsum([1;ix]); % rank
tix = reshape(tix(idx),yr,yc); % inverse sort rank
cc = 1;
tmp = sum(ix)+1;
if exist('OCTAVE_VERSION')>=5,
; % NOP; no support for integer datatyp
elseif tmp <= 2^8;
tix = uint8(tix);
cc = 8/1;
elseif tmp <= 2^16;
tix = uint16(tix);
cc = 8/2;
elseif tmp <= 2^32;
tix = uint32(tix);
cc = 8/4;
end;
R.compressionratio = (prod(size(R.X)) + (yr*yc)/cc) / (yr*yc);
R.tix = tix;
end;
% if yc==1, we are all set; else
if yc>1, % a few more steps are necessary
H0 = H; %overall histogram
% allocate memory
H = zeros(size(R.X,1),yc);
% scan each channel
for k = 1:yc,
sY = sort(Y(:,k));
ix = find(diff(sY,1)>0);
if size(ix,1)>0,
tmp = [ix; R.N(k)];
else
tmp = R.N(k);
end;
t = 0;
j = 1;
for x = tmp',
acc = sY(x);
while R.X(j)~=acc, j=j+1; end;
%j = find(sY(x)==R.X); % identify position on X
H(j,k) = H(j,k) + (x-t); % add diff(tmp)
t = x;
end;
end;
if any(H0~=sum(H,2)), %%% CHECK
fprintf(2,'ERROR HISTO\n');
end;
end;
R.H = H;
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